Revised Targets for Knee Radiofrequency Ablation (ReTaKRA)

Centro Hospitalar Universitario do Algarve

Status: Enrolling

Conditions: Osteoarthritis Knee Pain

Treatments: Device: Ultrasound-Guided Genicular Nerve Radiofrequency Ablation

Study type: Observational

Funder types: Other

Identifiers

NCT06934421

025/2025

Details and patient eligibility

About

This research team is doing a study to learn more about a new way to treat long-term knee pain caused by joint damage. They are using a treatment called radiofrequency ablation (RFA). This is a procedure where doctors use heat to stop certain nerves from sending pain signals.

In this study, doctors will use ultrasound to guide a small needle to nerves around the knee, called genicular nerves. Then, they will apply heat to those nerves using radiofrequency energy to help reduce pain.

The team created this new method based on recent studies of knee anatomy. They want to find out if this method can safely reduce pain and help people with knee joint damage move better. The study includes people who have moderate to severe knee damage and still have pain after trying medicine, physical therapy, or joint injections.

Each person in the study will have the treatment once. The research team will follow each person for two years. During this time, people in the study will answer simple questions about their knee pain and how it affects their daily life. The researchers will collect this information before the treatment and several times after it. One week after the procedure, the team will call each person to ask how they are feeling and check for any side effects.

Possible benefits of the study include less knee pain and easier movement. Possible risks include pain during the procedure, bruising, swelling, or short-term worsening of pain. Rare risks include nerve problems, weakness, bone damage, or allergic reaction.

The study is free for participants, and there is no payment. Taking part is voluntary. Anyone can stop being in the study at any time without affecting their medical care. The research team will keep all personal information private and secure.

Full description

This study applies a modified ultrasound-guided radiofrequency ablation (RFA) protocol for targeting the genicular nerves, informed by recent anatomical research. Conventional genicular nerve RFA techniques commonly rely on fluoroscopic or ultrasound guidance based on standard anatomical landmarks. However, cadaveric studies-such as those by Fonkoue et al. (2021)-have shown that these conventional approaches frequently miss the intended nerves, particularly the superomedial and superolateral branches, leading to inconsistent or suboptimal outcomes.

To address these limitations, this protocol incorporates revised probe positioning and alternative bony landmarks aligned with verified nerve pathways. The updated targeting strategy is designed to improve the precision and reproducibility of genicular nerve localization using high-resolution musculoskeletal ultrasound.

The procedure begins with ultrasound identification of the target genicular nerves. Once confirmed, a local anesthetic (2% lidocaine, 20-40 mg per site) is infiltrated to minimize discomfort. Thermal lesioning is then performed using standard 20G RF cannulas at 85°C for 90 seconds. Sensory stimulation (0.2-0.5 V) is used to verify appropriate referral patterns, and motor stimulation (2.0 V) is applied to rule out motor involvement before lesioning. If motor responses are elicited, repositioning or procedure cancellation is considered.

This anatomically informed technique aims to enhance procedural accuracy and consistency. By integrating cadaver-based nerve mapping with real-time ultrasound imaging, the approach has the potential to improve treatment effectiveness while maintaining a strong safety profile. The study will contribute clinical data supporting the feasibility and utility of this refined targeting method in managing knee pain related to joint degeneration.

Enrollment: 60 estimated patients

Sex: All

Ages: 18+ years old

Volunteers: No Healthy Volunteers

Inclusion criteria

• Patients with chronic knee pain related to radiographic knee osteoarthritis, Kellgren-Lawrence (KL) grade III or IV, who are refractory to conservative treatment.

(Refractoriness to conservative treatment is defined as:

• Persistent pain and functional limitation after undergoing knee-targeted physiotherapy and analgesic medication in accordance with clinical guidelines for osteoarthritis [e.g., paracetamol, nonsteroidal anti-inflammatory drugs, and other drugs as deemed appropriate by the treating physician];
• Persistent pain and functional limitation after intra-articular corticosteroid injections or limited success with such interventions.)

Exclusion criteria

• Patients with previous knee arthroplasty
• Patients who have undergone prior radiofrequency (RF) ablation
• Significant psycho-emotional disorders
• Addictive behaviors
• Generalized pain
• Nociplastic pain
• Presence of a pacemaker
• Presence of osteosynthesis material in the knee or adjacent anatomical regions

Trial design

60 participants in 1 patient group

Single-Session Ultrasound-Guided Genicular Nerve Radiofrequency Ablation in Patients With Knee Osteo

Description:

Participants with knee osteoarthrosis (Kellgran-Lawrence III or IV) will receive a single-session ultrasound-guided radiofrequency ablation of the genicular nerves. The procedure targets three specific nerve branches around the knee joint: the superomedial, superolateral, and inferomedial genicular nerves. The targeted positions are based on anatomical reference points described by Fonkoue et al. (2021) and validated in cadaveric studies, aiming to improve the accuracy of nerve localization. Under ultrasound guidance, the clinician will insert a radiofrequency needle at each target site. After confirming correct positioning through sensory and motor stimulation, thermal ablation will be performed at 85ºC for 90 seconds per site. Local anesthesia will be administered before each ablation to ensure patient comfort. This procedure aims to reduce knee pain and improve function in patients with moderate to severe knee joint degeneration who have not responded to conservative treatments.

Treatment:

Device: Ultrasound-Guided Genicular Nerve Radiofrequency Ablation